Withdrawal and gasification of cryogenic liquids from cryogenic vessels are the subjects of a number of patents.
U.S. Pat. No. 2,971,345 (Ball) contemplates a device for withdrawing liquid butane from a vessel. The device includes a storage vessel, a vaporizer and a pump. In operation, a portion of the butane withdrawn from the vessel is vaporized and subsequently recycled to the vessel. Another portion on the butane is sent to a receiving means.
U.S. Pat. No. 3,216,209 (Krigsman) is directed to an apparatus for maintaining a fluid in a supercritical state. The apparatus is provided with a heating coil within a storage vessel and a heating coil external to the storage vessel. Fluid that is withdrawn from the storage vessel flows through the heating coils to maintain it in a supercritical state.
U.S. Pat. No. 3,696,627 (Longsworth) discloses a system for transferring a liquefied gas at a constant temperature, pressure and flow rate. The system consists of three nested tubes. The innermost tube withdraws the liquefied gas. The middle tube subcools the liquefied gas in the inner tube and the outermost tube absorbs heat from the surrounding atmosphere through a jacketing fluid.
U.S. Pat. No. 4,317,269 (Martin et al.) discloses a device for revaporizing a liquefied gas that is stored in an insulated vessel. The device includes a series of nested tubes through which water flows. As the liquefied gas contacts the nested tubes, it is vaporized.
A significant disadvantage of prior systems for withdrawing and gasifying cryogenic liquids has been that the withdrawal rate is impeded or even stopped when the pressure of the gas in the head space above the liquid in the insulated vessel is lowered because the liquid is withdrawn faster than it can vaporize within the vessel and replenish the head pressure.